In X-ray fluorescence (XRF) testing, portable testing instruments are often subject to harsh environment. The instrument test windows often need to be protected from possible dusting, intrusion and abrasion from the test material.
However, applying protecting material to the test window often impedes the accuracy and sensitivity of the test result, particularly for testing elements with low atomic numbers.
For example, polyethylene or polyimide is often used material for window shields or a cover. Polyethylene is more transparent and therefore less of absorbing to low energy X-rays than polyimide, but is not as resistant to punctures.
It is therefore desirable to have the sensitivity that polyethylene yields for elements with lower atomic numbers, and with the same instrument to have the physical protection offered by thicker polyimide when the testing requirement for sensitivity is not as demanding, such as for testing Titanium (Ti) or other higher atomic numbers. It provides many benefits for an instrument to be equipped with a layer of window guard or protecting film that can be easily applied on or taken off for testing elements with higher or lower atomic numbers, respectively.
Various shields and/or window guards have been seen in existing practice designed for X-ray devices such as handheld X-ray fluorescence (XRF) instruments. Examples include U.S. patent Ser. No. 13/551,232; U.S. Pat. Nos. 7,430,274; 7,375,359; 7,375,358; 6,965,118; and 7,671,350, as well as WO 00/37928, are all incorporated herein by this reference. See also U.S. Published Application No. US-2008-0152079. However, none of these background arts have been seen to provide the simple, low cost and convenient solution as described herein in the present disclosure.